Network Automation and Infrastructure as Code

Every network engineer knows the feeling: you need to make a change to a production network, and your stomach tightens. Not because the change is complex—but because you're not entirely sure what else might break.

The terror of touching a production network comes from a single source: uncertainty. You don't know exactly what's configured. You don't know why it's configured that way. You don't know what will break if you change it.

Network automation and Infrastructure as Code exist to eliminate that uncertainty.

The Problem with Manual Networks

Traditional network operations look like this: an engineer logs into a device, types commands or pastes from a text file, hopes they got it right, then moves to the next device. Documentation exists somewhere—maybe a wiki, maybe a spreadsheet—but it's probably outdated. It was accurate when someone wrote it, but the network has changed since then.

Over time, these networks accumulate what you might call ghost configurations—settings that exist for forgotten reasons, that no one dares remove because no one remembers what they do. Each device becomes slightly different from its siblings. The network works, but no one fully understands it.

This isn't sustainable. As networks grow and changes become more frequent, the uncertainty compounds. Every change carries risk because you can't predict the consequences.

Configuration as Code

Infrastructure as Code inverts this dynamic. Instead of logging into devices and making changes, you describe the desired state of your network in code files. Tools read those files and make the network match what you've described.

The code lives in Git. Every change has an author, a timestamp, and a description of why it was made. Want to know why that ACL exists? Check the commit history. Need to restore last week's configuration? It's right there in version control.

This isn't just better documentation—it's the elimination of ghost configurations. If something exists in your network, it exists in code. If it's not in code, it shouldn't exist.

Declarative vs. Imperative

The key insight of IaC is declarative configuration. You don't write "add this route, remove that interface, modify this ACL." You write "the network should look like this." The tools figure out what changes are needed to make reality match your description.

This matters because it makes configurations idempotent—you can apply them repeatedly and get the same result. Apply the same configuration to a hundred devices and they'll all match. Apply it again tomorrow and nothing changes (because they already match).

Declarative configuration also enables drift detection. If someone makes a manual change, the next automated run will either fix it or flag it. The code remains the source of truth.

The Tooling Landscape

Terraform uses HashiCorp Configuration Language to define infrastructure across cloud providers and on-premises equipment. It excels at managing cloud networking—VPCs, subnets, security groups—and increasingly supports physical network devices.

Ansible uses YAML playbooks and operates agentlessly over SSH. It's particularly popular for network automation because it doesn't require installing anything on network devices.

NETCONF/YANG provides a standard protocol and data model for network configuration. YANG defines the structure of configuration data; NETCONF provides the transport. Where supported, they enable truly vendor-neutral automation.

Nornir is a Python framework built specifically for network automation, giving you programmatic control when YAML playbooks aren't flexible enough.

The choice depends on your environment. Cloud-heavy? Terraform. Mixed physical and virtual? Ansible. Need deep customization? Nornir. Many organizations use multiple tools for different parts of their infrastructure.

APIs: The Foundation

Automation requires APIs. Modern network devices expose several:

NETCONF uses XML and provides transactional configuration—changes either fully apply or fully roll back.

RESTCONF offers the same data models over HTTP, more familiar to developers used to web APIs.

gRPC enables high-performance streaming, increasingly used for real-time telemetry.

Legacy devices without APIs create automation challenges. You can scrape CLI output, but it's fragile—any change to output formatting breaks your scripts. This is often the biggest obstacle to full network automation: not the new devices, but the old ones that will never have proper APIs.

GitOps: Git as Source of Truth

GitOps extends IaC by making Git the authoritative source for network state:

1. All configuration lives in Git repositories
2. Changes go through pull requests with peer review
3. Automated tests validate changes before merge
4. Merging to main triggers deployment to the network
5. Git history becomes your complete audit trail

Want to know every change made to your network in the last year? It's all in Git. Need to roll back a bad change? Revert the commit. Wondering who approved that firewall rule? Check the pull request.

This transforms change management from a bureaucratic process into a natural part of development workflow.

Testing Before Production

Automated testing catches errors that manual review misses:

Syntax validation ensures configurations are well-formed before deployment attempts.

Policy compliance verifies configurations meet security requirements—no default passwords, no overly permissive ACLs.

Dry-run deployments show exactly what will change without making changes. Review the diff before committing to it.

Integration tests verify network functionality after deployment. Can traffic flow where it should? Are routes correct?

Continuous validation detects drift between desired state and actual state, catching manual changes or unexpected modifications.

The goal is making it harder to deploy bad configurations than good ones.

Intent-Based Networking

Intent-based networking represents the next evolution. Instead of specifying configurations, you specify outcomes: "Guest traffic should be isolated from corporate traffic with appropriate QoS."

The system translates that intent into device-specific configurations. When conditions change—new devices added, links fail—the system adapts automatically while maintaining the stated intent.

This is still emerging technology, but it points toward networks that truly manage themselves, with humans defining policy rather than configuration.

CI/CD for Networks

Continuous Integration and Continuous Deployment, standard practice for applications, applies equally to networks:

1. Engineer commits configuration change to Git
2. CI pipeline runs automated tests
3. Successful tests deploy to staging environment
4. Validation in staging gates production deployment
5. Production deployment proceeds (automatically or with approval)

This pipeline makes network changes as reliable as application deployments—tested, reviewed, and traceable.

The Obstacles Are Real

Legacy devices may never support automation properly. You'll need to decide whether to replace them or work around them.

Vendor differences create complexity. Each vendor has different APIs, different commands, different data models. Abstraction layers help but can't eliminate this entirely.

Skills gaps exist. Network engineers often lack programming experience; software engineers often lack network knowledge. Building automation expertise takes time.

Cultural resistance is common. Teams accustomed to manual work may see automation as threatening their jobs rather than augmenting their capabilities.

Risk aversion makes organizations hesitant to automate critical infrastructure. The irony is that manual processes are typically riskier—but they're familiar risks.

None of these obstacles are insurmountable. But they're real, and pretending otherwise leads to failed automation initiatives.

Security: Better and Worse

Automation improves security in obvious ways: consistent configurations across devices, rapid deployment of security fixes, complete audit trails of every change.

But it also creates new attack surfaces. Your automation system can configure every device in your network—what happens if it's compromised? Secrets management becomes critical. The principle of least privilege applies to automation systems as much as human accounts.

The net effect is usually positive, but you're trading one set of security considerations for another.

The Real Transformation

Network automation isn't really about tools or APIs or CI/CD pipelines. It's about transforming networks from mysterious systems that no one fully understands into predictable infrastructure that behaves consistently.

When your network configuration is code, you can understand it. When changes go through version control, you can trace them. When deployments are automated, you can trust them.

The stomach-tightening moment before a production change doesn't have to exist. Not because the network is simpler—but because you finally know exactly what's configured, why it's configured that way, and what will happen when you change it.